The increase in dye density of unexposed areas in color photographic light-sensitive material on application of color development (in the case of reversal light-sensitive material, the dye density of unexposed areas decreases) is called "formation of color development fog", This phenomenon usually occurs more readily with an increase in the sensitivity of color photographic light-sensitive materials. The phenomenon is also more likely to occur as the period for which the color photographic light-sensitive material is stored is lengthened. Furthermore, the phenomenon occurs more readily if the light-sensitive material is stored in a higher temperature or humidity. Moreover, as the color developing temperature is increased, the phenomenon occurs more easily. It is preferable to control the formation of color development fog to as low a level as possible since wt causes deterioration of photographic properties, e.g., a reduction in image contrast.
In order to prevent the formation of color development fog, there has heretofore been used a method in which substances called "antifoggants" are incorporated into light-sensitive materials or developers. A number of compounds are known as antifoggants. Of these compounds, 1-phenyl-5-mercaptotetrazole is most widely used. This compound, however, is not suitable particularly for a forced development, in which a time for development (including first development in a reversal development) is lengthened than a normal developing time (which is usually specified by each maker of a photographic light-sensitive material although the normal developing time varies due to a development processing, see, Photo. Lab. Index, Morgan & Morgan Inc., etc.) so as to obtain higher sensitivity than the sensitivity obtained by the normal developing time, since it often causes a considerable reduction in sensitivity due to its too high ability to prevent color development.
Other known antifoggants include 1-phenyl-5-mercaptotetrazole derivatives, as described in U.S. Pat. No. 3,266,897, in which the phenyl group is substituted by two carboxyl groups. However, these compounds are not good for preventing the formation of color development fog for light-sensitive materials which have been stored under high temperature and humidity conditions.